Improve svg-flatten document scale error messages

svg-flatten/src/out_gerber.cpp

@@ -52,6 +52,7 @@ void SimpleGerberOutput::header_impl(d2p origin, d2p size) {
     
     if (pow(10, m_digits_int-1) < max(m_width, m_height)) {
         cerr << "Warning: Input has bounding box too large for " << m_digits_int << "." << m_digits_frac << " gerber resolution!" << endl;
+        cerr << "         Bounding box in gerber units: " << m_width << " x " << m_height << endl;
     }
 
     m_out << "%FSLAX" << m_digits_int << m_digits_frac << "Y" << m_digits_int << m_digits_frac << "*%" << endl;

svg-flatten/src/svg_doc.cpp

@@ -92,6 +92,7 @@ bool gerbolyze::SVGDocument::load(istream &in, double scale) {
 
     if (fabs((vb_w / page_w) / (vb_h / page_h) - 1.0) > 0.001) {
         cerr << "Warning: Document has different document unit scale in x and y direction! Output will likely be garbage!" << endl;
+        cerr << "         Viewbox size " << vb_w << " x " << vb_h << ", document size " << page_w << " x " << page_h << " -> scale " << (vb_w/page_w) << " x " << (vb_h/page_h) << endl;
     }
 
     cerr << "Resulting page width " << page_w_mm << " mm x " << page_h_mm << " mm" << endl;